Table 2. Psychometric properties of the Epworth Sleepiness Scale for Children in item level .

Item #	Item score	Item score	Analyses from classical test theory			Analyses from Rasch
	Median	Mean (SD)	Factor loading a	Item-total correlation	Test-retest b	Infit MnSq	Outfit MnSq	Difficulty	DIF contrast across gender cd	DIF contrast across living condition ce	DIF contrast across insomnia condition cfg
ESS-CHAD1	1	0.75 (0.89)	0.66	0.65	0.73	0.89	0.99	0.09	-0.06	0.04	-0.13
ESS- CHAD2	1	0.72 (1.17)	0.75	0.53	0.77	1.31	1.19	0.15	0.38	-0.07	-0.27
ESS- CHAD3	0	0.70 (0.91)	0.65	0.70	0.78	0.88	0.88	0.22	0.18	0.10	-0.43
ESS- CHAD4	1	1.12 (1.06)	0.62	0.76	0.80	1.14	1.13	-0.58	-0.06	0.01	-0.11
ESS- CHAD5	2	1.84 (1.12)	0.79	0.66	0.86	1.06	1.10	-1.24	-0.06	0.01	0.01
ESS- CHAD6	0	0.19 (0.48)	0.75	0.75	0.82	0.90	0.68	1.36	0.08	0.24	-0.09
ESS- CHAD7	1	1.15 (1.08)	0.83	0.65	0.74	0.99	0.94	-0.63	-0.08	-0.03	0.04
ESS- CHAD8	0	0.52 (0.64)	0.78	0.71	0.72	1.10	1.06	0.62	-0.31	-0.11	-0.06

ESS-CHAD= Epworth Sleepiness Scale for Children and Adolescents, Total EDSS-CHAD score: mean (SD)= 7.91 (4.35)

^a Based on the first-order confirmatory factor analysis.

^b Using intraclass correlation coefficient (ICC).

^c DIF contrast > 0.5 indicates substantial DIF.

^d DIF contrast across gender=Difficulty for females-Difficulty for males.

^e DIF contrast across living condition= Difficulty for participants with private bedroom - Difficulty for participants without private bedroom MnSq=mean square error; DIF=differential item functioning.

^fDIF contrast across insomnia condition= Difficulty for participants with insomnia - Difficulty for participants without insomnia.

^gBased on the cutoff score of 10 in the Insomnia Severity Index.